摘要
In the data processing of the precise point positioning (PPP), the un-difference method is commonly used. However, GPS measurements can be differenced with satellites or different observation epochs. In theory,these differencing approaches should be mathematically equivalent. The positioning performance of different PPP data models, including un-difference (UD), satellite difference (SD), time difference (TD) and time-satellite difference (TSD), is examined using the 24 h GPS observation. The positioning accuracy, convergence of ambiguity, and tropspheric delay estimation with these four models are compared with each other.
